1 files changed, 325 insertions, 0 deletions
diff --git a/src/cmd/dist/buildtool.go b/src/cmd/dist/buildtool.go
new file mode 100644
index 0000000..cf85f2a
--- /dev/null
+++ b/src/cmd/dist/buildtool.go
@@ -0,0 +1,325 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Build toolchain using Go 1.4.
+//
+// The general strategy is to copy the source files we need into
+// a new GOPATH workspace, adjust import paths appropriately,
+// invoke the Go 1.4 go command to build those sources,
+// and then copy the binaries back.
+
+package main
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"runtime"
+	"strings"
+)
+
+// bootstrapDirs is a list of directories holding code that must be
+// compiled with a Go 1.4 toolchain to produce the bootstrapTargets.
+// All directories in this list are relative to and must be below $GOROOT/src.
+//
+// The list has have two kinds of entries: names beginning with cmd/ with
+// no other slashes, which are commands, and other paths, which are packages
+// supporting the commands. Packages in the standard library can be listed
+// if a newer copy needs to be substituted for the Go 1.4 copy when used
+// by the command packages.
+// These will be imported during bootstrap as bootstrap/name, like bootstrap/math/big.
+var bootstrapDirs = []string{
+	"cmd/asm",
+	"cmd/asm/internal/arch",
+	"cmd/asm/internal/asm",
+	"cmd/asm/internal/flags",
+	"cmd/asm/internal/lex",
+	"cmd/cgo",
+	"cmd/compile",
+	"cmd/compile/internal/amd64",
+	"cmd/compile/internal/arm",
+	"cmd/compile/internal/arm64",
+	"cmd/compile/internal/gc",
+	"cmd/compile/internal/logopt",
+	"cmd/compile/internal/mips",
+	"cmd/compile/internal/mips64",
+	"cmd/compile/internal/ppc64",
+	"cmd/compile/internal/riscv64",
+	"cmd/compile/internal/s390x",
+	"cmd/compile/internal/ssa",
+	"cmd/compile/internal/syntax",
+	"cmd/compile/internal/types",
+	"cmd/compile/internal/x86",
+	"cmd/compile/internal/wasm",
+	"cmd/internal/bio",
+	"cmd/internal/codesign",
+	"cmd/internal/gcprog",
+	"cmd/internal/dwarf",
+	"cmd/internal/edit",
+	"cmd/internal/goobj",
+	"cmd/internal/objabi",
+	"cmd/internal/obj",
+	"cmd/internal/obj/arm",
+	"cmd/internal/obj/arm64",
+	"cmd/internal/obj/mips",
+	"cmd/internal/obj/ppc64",
+	"cmd/internal/obj/riscv",
+	"cmd/internal/obj/s390x",
+	"cmd/internal/obj/x86",
+	"cmd/internal/obj/wasm",
+	"cmd/internal/pkgpath",
+	"cmd/internal/src",
+	"cmd/internal/sys",
+	"cmd/link",
+	"cmd/link/internal/amd64",
+	"cmd/link/internal/arm",
+	"cmd/link/internal/arm64",
+	"cmd/link/internal/benchmark",
+	"cmd/link/internal/ld",
+	"cmd/link/internal/loadelf",
+	"cmd/link/internal/loader",
+	"cmd/link/internal/loadmacho",
+	"cmd/link/internal/loadpe",
+	"cmd/link/internal/loadxcoff",
+	"cmd/link/internal/mips",
+	"cmd/link/internal/mips64",
+	"cmd/link/internal/ppc64",
+	"cmd/link/internal/riscv64",
+	"cmd/link/internal/s390x",
+	"cmd/link/internal/sym",
+	"cmd/link/internal/x86",
+	"compress/flate",
+	"compress/zlib",
+	"cmd/link/internal/wasm",
+	"container/heap",
+	"debug/dwarf",
+	"debug/elf",
+	"debug/macho",
+	"debug/pe",
+	"internal/goversion",
+	"internal/race",
+	"internal/unsafeheader",
+	"internal/xcoff",
+	"math/big",
+	"math/bits",
+	"sort",
+}
+
+// File prefixes that are ignored by go/build anyway, and cause
+// problems with editor generated temporary files (#18931).
+var ignorePrefixes = []string{
+	".",
+	"_",
+}
+
+// File suffixes that use build tags introduced since Go 1.4.
+// These must not be copied into the bootstrap build directory.
+// Also ignore test files.
+var ignoreSuffixes = []string{
+	"_arm64.s",
+	"_arm64.go",
+	"_riscv64.s",
+	"_riscv64.go",
+	"_wasm.s",
+	"_wasm.go",
+	"_test.s",
+}
+
+func bootstrapBuildTools() {
+	goroot_bootstrap := os.Getenv("GOROOT_BOOTSTRAP")
+	if goroot_bootstrap == "" {
+		goroot_bootstrap = pathf("%s/go1.4", os.Getenv("HOME"))
+	}
+	xprintf("Building Go toolchain1 using %s.\n", goroot_bootstrap)
+
+	mkzbootstrap(pathf("%s/src/cmd/internal/objabi/zbootstrap.go", goroot))
+
+	// Use $GOROOT/pkg/bootstrap as the bootstrap workspace root.
+	// We use a subdirectory of $GOROOT/pkg because that's the
+	// space within $GOROOT where we store all generated objects.
+	// We could use a temporary directory outside $GOROOT instead,
+	// but it is easier to debug on failure if the files are in a known location.
+	workspace := pathf("%s/pkg/bootstrap", goroot)
+	xremoveall(workspace)
+	xatexit(func() { xremoveall(workspace) })
+	base := pathf("%s/src/bootstrap", workspace)
+	xmkdirall(base)
+
+	// Copy source code into $GOROOT/pkg/bootstrap and rewrite import paths.
+	writefile("module bootstrap\n", pathf("%s/%s", base, "go.mod"), 0)
+	for _, dir := range bootstrapDirs {
+		src := pathf("%s/src/%s", goroot, dir)
+		dst := pathf("%s/%s", base, dir)
+		xmkdirall(dst)
+		if dir == "cmd/cgo" {
+			// Write to src because we need the file both for bootstrap
+			// and for later in the main build.
+			mkzdefaultcc("", pathf("%s/zdefaultcc.go", src))
+		}
+	Dir:
+		for _, name := range xreaddirfiles(src) {
+			for _, pre := range ignorePrefixes {
+				if strings.HasPrefix(name, pre) {
+					continue Dir
+				}
+			}
+			for _, suf := range ignoreSuffixes {
+				if strings.HasSuffix(name, suf) {
+					continue Dir
+				}
+			}
+			srcFile := pathf("%s/%s", src, name)
+			dstFile := pathf("%s/%s", dst, name)
+			text := bootstrapRewriteFile(srcFile)
+			writefile(text, dstFile, 0)
+		}
+	}
+
+	// Set up environment for invoking Go 1.4 go command.
+	// GOROOT points at Go 1.4 GOROOT,
+	// GOPATH points at our bootstrap workspace,
+	// GOBIN is empty, so that binaries are installed to GOPATH/bin,
+	// and GOOS, GOHOSTOS, GOARCH, and GOHOSTOS are empty,
+	// so that Go 1.4 builds whatever kind of binary it knows how to build.
+	// Restore GOROOT, GOPATH, and GOBIN when done.
+	// Don't bother with GOOS, GOHOSTOS, GOARCH, and GOHOSTARCH,
+	// because setup will take care of those when bootstrapBuildTools returns.
+
+	defer os.Setenv("GOROOT", os.Getenv("GOROOT"))
+	os.Setenv("GOROOT", goroot_bootstrap)
+
+	defer os.Setenv("GOPATH", os.Getenv("GOPATH"))
+	os.Setenv("GOPATH", workspace)
+
+	defer os.Setenv("GOBIN", os.Getenv("GOBIN"))
+	os.Setenv("GOBIN", "")
+
+	os.Setenv("GOOS", "")
+	os.Setenv("GOHOSTOS", "")
+	os.Setenv("GOARCH", "")
+	os.Setenv("GOHOSTARCH", "")
+
+	// Run Go 1.4 to build binaries. Use -gcflags=-l to disable inlining to
+	// workaround bugs in Go 1.4's compiler. See discussion thread:
+	// https://groups.google.com/d/msg/golang-dev/Ss7mCKsvk8w/Gsq7VYI0AwAJ
+	// Use the math_big_pure_go build tag to disable the assembly in math/big
+	// which may contain unsupported instructions.
+	// Note that if we are using Go 1.10 or later as bootstrap, the -gcflags=-l
+	// only applies to the final cmd/go binary, but that's OK: if this is Go 1.10
+	// or later we don't need to disable inlining to work around bugs in the Go 1.4 compiler.
+	cmd := []string{
+		pathf("%s/bin/go", goroot_bootstrap),
+		"install",
+		"-gcflags=-l",
+		"-tags=math_big_pure_go compiler_bootstrap",
+	}
+	if vflag > 0 {
+		cmd = append(cmd, "-v")
+	}
+	if tool := os.Getenv("GOBOOTSTRAP_TOOLEXEC"); tool != "" {
+		cmd = append(cmd, "-toolexec="+tool)
+	}
+	cmd = append(cmd, "bootstrap/cmd/...")
+	run(base, ShowOutput|CheckExit, cmd...)
+
+	// Copy binaries into tool binary directory.
+	for _, name := range bootstrapDirs {
+		if !strings.HasPrefix(name, "cmd/") {
+			continue
+		}
+		name = name[len("cmd/"):]
+		if !strings.Contains(name, "/") {
+			copyfile(pathf("%s/%s%s", tooldir, name, exe), pathf("%s/bin/%s%s", workspace, name, exe), writeExec)
+		}
+	}
+
+	if vflag > 0 {
+		xprintf("\n")
+	}
+}
+
+var ssaRewriteFileSubstring = filepath.FromSlash("src/cmd/compile/internal/ssa/rewrite")
+
+// isUnneededSSARewriteFile reports whether srcFile is a
+// src/cmd/compile/internal/ssa/rewriteARCHNAME.go file for an
+// architecture that isn't for the current runtime.GOARCH.
+//
+// When unneeded is true archCaps is the rewrite base filename without
+// the "rewrite" prefix or ".go" suffix: AMD64, 386, ARM, ARM64, etc.
+func isUnneededSSARewriteFile(srcFile string) (archCaps string, unneeded bool) {
+	if !strings.Contains(srcFile, ssaRewriteFileSubstring) {
+		return "", false
+	}
+	fileArch := strings.TrimSuffix(strings.TrimPrefix(filepath.Base(srcFile), "rewrite"), ".go")
+	if fileArch == "" {
+		return "", false
+	}
+	b := fileArch[0]
+	if b == '_' || ('a' <= b && b <= 'z') {
+		return "", false
+	}
+	archCaps = fileArch
+	fileArch = strings.ToLower(fileArch)
+	fileArch = strings.TrimSuffix(fileArch, "splitload")
+	if fileArch == os.Getenv("GOHOSTARCH") {
+		return "", false
+	}
+	if fileArch == strings.TrimSuffix(runtime.GOARCH, "le") {
+		return "", false
+	}
+	if fileArch == strings.TrimSuffix(os.Getenv("GOARCH"), "le") {
+		return "", false
+	}
+	return archCaps, true
+}
+
+func bootstrapRewriteFile(srcFile string) string {
+	// During bootstrap, generate dummy rewrite files for
+	// irrelevant architectures. We only need to build a bootstrap
+	// binary that works for the current runtime.GOARCH.
+	// This saves 6+ seconds of bootstrap.
+	if archCaps, ok := isUnneededSSARewriteFile(srcFile); ok {
+		return fmt.Sprintf(`// Code generated by go tool dist; DO NOT EDIT.
+
+package ssa
+
+func rewriteValue%s(v *Value) bool { panic("unused during bootstrap") }
+func rewriteBlock%s(b *Block) bool { panic("unused during bootstrap") }
+`, archCaps, archCaps)
+	}
+
+	return bootstrapFixImports(srcFile)
+}
+
+func bootstrapFixImports(srcFile string) string {
+	lines := strings.SplitAfter(readfile(srcFile), "\n")
+	inBlock := false
+	for i, line := range lines {
+		if strings.HasPrefix(line, "import (") {
+			inBlock = true
+			continue
+		}
+		if inBlock && strings.HasPrefix(line, ")") {
+			inBlock = false
+			continue
+		}
+		if strings.HasPrefix(line, `import "`) || strings.HasPrefix(line, `import . "`) ||
+			inBlock && (strings.HasPrefix(line, "\t\"") || strings.HasPrefix(line, "\t. \"") || strings.HasPrefix(line, "\texec \"")) {
+			line = strings.Replace(line, `"cmd/`, `"bootstrap/cmd/`, -1)
+			// During bootstrap, must use plain os/exec.
+			line = strings.Replace(line, `exec "internal/execabs"`, `"os/exec"`, -1)
+			for _, dir := range bootstrapDirs {
+				if strings.HasPrefix(dir, "cmd/") {
+					continue
+				}
+				line = strings.Replace(line, `"`+dir+`"`, `"bootstrap/`+dir+`"`, -1)
+			}
+			lines[i] = line
+		}
+	}
+
+	lines[0] = "// Code generated by go tool dist; DO NOT EDIT.\n// This is a bootstrap copy of " + srcFile + "\n\n//line " + srcFile + ":1\n" + lines[0]
+
+	return strings.Join(lines, "")
+}